The Biostatistics/Data Management Center - M.D. Anderson Cancer Center (MDACC) will provide the Primary Data Management and Biostatistical support for Projects 3, 4, and 6, and support the Data Management and Statistical Activities of the RTOG Center for Project 1 and 2. For Project 1 (Chemoprevention Study), the MDACC Center will be the contact office for registration and randomization of CCOP and MDACC patients; receive, edit, and transmit data forms from CCOPs and MDACC to the RTOG office; perform toxicity monitoring for CCOP and MDACC; directly receive, log-in, and transmit all pathology, laboratory specimens, and radiologic meterials. The MDACC Core will receive and track all specimens for Project 2 (Risk Model Study). The core will periodically survey and enter data for Projects 4 (Field Cancerization) and 6 (Role of NRARs in Retinoid Response). For Project 3 (Leukoplakia Study), the core will register and randomize patients; collect and monitor data; perform quality assurance activities; monitor toxicity; and track biologic specimens. The Biostatistics Unit of the core will provide primary statistical analysis for Project 3, 4, and 6 and collaborate with the RTOG Biostatistical Unit for Projects 1 and 2. The establishment of the MDACC Center, closely linked to the RTOG Center, will enable the program to utilize existing, well-established Data Management linkages with the CCOPs, and maintain on-site Data Management and Biostatistical support for projects being performed at MDACC. The Data-Management Office of the Section of Community Oncology and the Biostatistics Resource Group at MDACC have on-going experience with multi-disciplinary, multi-institutional trials and thus are able to utilize firmly established facilities and resources in accomplishing these tasks. The close relationship developed over the last two years with the RTOG Biostatistics/Data Management Center will ensure the smooth integration of the activities of these two components.